Weigh the benefits of on-site nitrogen generation

Many facilities are turning to on-site nitrogen generation as a more effective problem-solver that helps operations run efficiently.

Paul Humphreys, Atlas Copco

03/07/2011

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Nitrogen gas is a critical component in a number of industrial markets, and innovative engineers are continuing to find new problem-solving applications in today’s manufacturing facilities. With greater emphasis on cost-effective, low-impact business practices, many facilities are turning to on-site nitrogen generation as a more effective problem-solver that helps operations run efficiently

Cost savings

Quite simply, manufacturers can realize savings somewhere in the range of 40% to 80% when shifting to on-site nitrogen generation, depending on current liquid nitrogen market prices. Prices for delivered liquid nitrogen in the industrial marketplace can range from $0.35 per hundred cubic feet to $1.50 per hundred cubic feet. In cylinders, the price can jump as high as $3 per hundred cubic feet. Shifting to use of an on-site nitrogen generation can initially drop costs to around $0.21 per hundred cubic feet. And that’s just the beginning.

In some scenarios, even after considering the capital costs associated with onsite nitrogen generation (costs such as generators, air compressors, receivers, site preparation, power and maintenance), customers can realize a return on investment in as few as two years. In each subsequent year, regular operational expenses can drop even further to about $0.11 per hundred cubic feet – just maintenance and energy costs. These savings do not include supplementary costs from nitrogen suppliers, which vary by region.

On-site nitrogen equipment providers such as Atlas Copco work with manufacturers to develop a spreadsheet to help them identify the savings that are waiting with a shift from delivered liquid nitrogen to on-site generation in a variety of industries. A set number of variables – liquid nitrogen costs per hundred cubic feet, tank rental fees, delivery charges, hazmat charges and numerous other miscellaneous costs are regular sights on delivery invoices.

Delivery of liquid nitrogen requires that the nitrogen gas be converted to liquid nitrogen for truck transport, and converted back to nitrogen gas onsite upon arrival. Product loss from these two filling points – nitrogen facility to truck and truck to manufacturing facility – contributes to exponential product waste, with additional charges for delivery costs on top of that.

Delivered nitrogen must also be stored onsite prior to use. In a cooled tank, customers who have nitrogen delivered to their facility will lose an automatic 10% of the delivery volume to waste. Furthermore, a tank with a good vacuum will lose a minimum of .4% of the volume each day if internal pressures are allowed to build when product off the top of the tank is not immediately used. Purging pressure to alleviate this pressure contributes additional unnecessary waste as well. It’s a no-win situation.

Environmentally beneficial

Tagging manufacturing practices and processes as “green” has become commonplace and many consumers now look beyond this trite term. Some organizations even deemed it one of the most overused words in 2008. Today, customers look for hard, measurable facts in order to determine for themselves whether a product’s environmental benefits truly stand on their own.

Making liquid nitrogen requires a great deal of electric energy, as the liquefaction point of nitrogen is below -320 degrees F. We’ve all seen videos of what happens when a rose is dipped in liquid nitrogen and dropped on the floor.

As visual a clue as that is, 80% of uses for nitrogen are as a gas and not a liquid. The only reason it is liquefied is for ease of transportation, which, as indicated above, contributes to loss on two fronts. Couple the use of diesel fuel and carbon emissions associated with truck delivery and there are easily identifiable and jargon-free environmental benefits to on-site generation. On-site nitrogen generation also reduces potential for worker injury associated with storage tank leaks and possible exposure to the -320 degree Fahrenheit liquid nitrogen. Serious burns from exposure to skin are dangerous and very possible.

Industry usage

Nitrogen gas is essential in a wide variety of manufacturing industries and environments. Food manufacturing facilities, utilities, such as oil, gas and other power generation facilities, electronics, chemical and pharmaceutical operations each rely on nitrogen gas for a number of applications.

In some industries, in remote or hard-to-reach locations where vehicular delivery is completely unfeasible, like offshore drilling and mining, having membrane or PSA supply nitrogen applications on-site is standard procedure. On-site nitrogen generation can also help achieve optimal purity levels; in industries with particularly sensitive or delicate applications like pharmaceutical, electronics and chemical manufacturing fields, where nitrogen purity is a gold standard, on-site nitrogen generation can better meet these requirements.

With minimal to no training, manufacturers in a number of industries can optimize performance while lowering costs and their facility’s carbon footprint with a simple shift from delivery to on-site nitrogen generation. Email for a copy, with the subject: Manual - Plant Engineering, of Atlas Copco's 136-page Compressed Air Manual 7th Edition.